View Full Version : animate/rig oval shaped object rolling?

Dark Soldier
04 April 2006, 12:54 PM

what do u tnink is the best way to animate/rig something oval shaped rolling.

kinda stuck, anything help appricated

04 April 2006, 01:30 PM
If you mean what I think you mean, you could try using Reactor. You know how weebles move? If you model a hollow object, make it into a rigid body then put a heavy ball inside it, the ball will weigh it down and cause it to move in this way.

It can, however, be very unpredictable and takes a lot of work to get it right!


05 May 2006, 12:16 AM
Hmm lots of ways, you could so some heavy sine algorithms to compensate the z axis. You could do a frame track check to see if its gone through the floor and raise it - this wont deal with the x position though as you may get sliding.Also if your going up a slop youd have to do a normal check, maybe ray intersect?, the other way is just hand animating the z position to compensate.


Dark Soldier
05 May 2006, 09:32 AM
hi eek

thanks for suggestions. was hoping there would be some kinda script or something. tried a load of stuff with some paths and other random things. if i get any where with i tell you how i did.

thanks again

05 May 2006, 01:37 PM
Maya solution: this is a rough, rough hack, but works for me, and can take into account a non-uniform surface.

Have a ground control which will set the surface upon which your object will roll.

Place locators on the surface along the edge which will be rolled on (or simply on the surface itself, if it will be rotating along more than an edge)

Parent locators under ground control.

Create rolling control.

Parent under ground control.

Parent constrain locators to rolling control.

Set up a nodal network with the Condition node. Basically its a pyramid which sorts through all the locators that you've made, and finds the one with the greatest -y value (aka, the locator is the lowest locator beneath the ground plane). It's essentially a comparison between two locators, find lowest y, then
the next level is comparing the resulting value with a similar resulting value from another condition node. Continue until there is one condition node, giving you the lowest locator.

Group the geometry twice. Feed the result from the condition node into the translate Y of the top group. Feed the translation and rotation of the rolling control into the second. Parent the top group under the ground control.

So in the end, you have a system which does a comparison between where the shape would be, and offsets the object accordingly, to prevent penetration of the groundplane.

More locators = more accurate & slower.

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